520 



CEEEBELLUM. 



form process ; but a considerable number of their fibres pass into or issue from 

 the grey capsule of the corpus dentatum. 



Fig. 365. 



^r^v(<^<Qrv(^ 



■o, septal fibres of tli 



into the laminaj of the cerebellum 



thalamus ; v corpus albicans, 



Fig. 365. — The Columns of the 

 Medulla Oblongata traced 

 upwards into the cerebellum 

 AND Cerebrum (from Arnold), g 



a, i^art of the anterior column 

 which ascends in the olivary column ; 

 b, decussating portion of the lateral 

 column forming the iij'ramid and 

 turn down ; c, olivary fasciculus 

 ascending deeply through the pons ; 

 d, olivary body ; e, restiform body ; 

 /, [/, corpora qiiadrigemina ; c, It, i, 

 the fillet ; h, the part which ascends 

 to the cerebral peduncle ; i, ' the 

 part passing uj) to the corpora 

 quadrigemina ; m, m, the trans- 

 verse fibres of the pons divided ; »?, 

 inferior peduncle of the cerebellum ; 

 medulla oblongata ; q, fibres of the inferior peduncle continued 

 sujDerior peduncle ; t, fasciculus teres ; u, 



A very different account from that which has generally been received of the 

 coui-se and relations of the tracts of neiTOus substance of the cerebellum has 

 recently been put forward by Luys, but has not yet received corroboration. 

 According to the statement of this author, all the fibres of the cerebellar i^eduncles 

 arise from the interior of the corpora dentata ; the cells of those centres receive 

 externally fibres from the laminated periphery of the cerebellum, and internally 

 give origin to the peduncular fibres ; the fibres of the inferior peduncles of 

 opposite sides cross the middle line and teiTainate in the interior of the olivary 

 nuclei ; and the fibres of the superior peduncles, likewise decussating in the 

 mesial plane before quitting the cerebellum, terminate in a grey centre of the 

 interior of the tegmentum of the cms cerebri, and thus the fibres of the 

 cerebellum form a separate system indirectly connected with the fibres of the 

 rest of the cerebro-spinal axis. (Luys, in Journ. de I'Anat. et de Physiol., 1864, 

 p. 225.) 



Minute Structure. — The cortical grey substance is composed of an 

 external clear grey layer, an inner greyish-red " granule " layer, and 

 between the two a single layer of large cells with long processes, 

 termed the corpuscles of Purkinje. Outside all is the layer of fibres 

 and vessels of the pia mater. 



The external layer (fig. 366, h) consists of a delicate matrix, probably 

 of the nature of connective tissue, containing cells and fibres. Most of 

 the fibres have a direction at right angles to the surface ; the greater 

 part of them are the processes of the large nerve cells which lie between 

 the two layers. Others are fine connective tissue fibres, analagous 

 to the sustentacular fibres of the retina, and connected by a broad base 

 with the pia-matral covering. The corpuscles are granule-like bodies, 

 some very small, and connected probably with the connective tissue 

 matrix, others larger and surrounded by protoplasm from which pro- 

 cesses extend. Some of the corpuscles are connected with the processes 

 of the larger cells.* (See fig. 367.) The inner part of this layer, con- 



* A connection described by Lockhart Clarke (Proc. Roy. Soc, 1863), and sub- 

 sequently by Obersteiner, and recently confirmed (independently) by Mr. H. R. 0. Sankey, 

 student of University College. 



